Portable radio receiver



June 27, 1939. E. F. McDoNALD, JR

PORTABLE RADIO RECEIVER Filed May 4, 1939 2 Sheets-Sheet l I Eu/Lanta?? /IMQ n. //W/4a n lgen@ Zjc 0 June 27, 1939. E. F. MCDONALD, JR

PORTABLE RADIO RECEIVER Filed May 4, 1959 2 Sheets-Sheet 2 Arf r m Patented June 27, 1.939

UNITE-D STATESl lMTENT oEFI-CE -roR'rlmLE Ramo REoErvEn Eugene McDonald, Jr., Chicago, Ill. Application May 4, 1939, serial N0. 271,653

c claims, (c1. 25o-14) -This invention relates to radio receiving apparatus, and more particularly concerns a novel construction and arrangement of a loopantenna forming a part of such apparatus.

The object of the invention is to provide a simple and eillcient construction through which the signal-receiving properties of a radio receiving set may be greatly increased and improved, and through which radio receiving sets of the loop antenna type maybe satisfactorily used in locations and under circumstances heretofore considered to be impracticable.

It is well known to those familiar with the radio art that, in radio receiving sets e'mploying a loop antenna, the directsignal input from the loop is comparatively weak and that, while sets of this type have been constructed to operate satisfactorily under some conditions, their sensitivity or signal pick-up qualifications are greatly diminished if they are placed too near metal structures. This is quite apparent if such a set is moved into and from close proximity to the beams or posts in the walls of a steel framed building, and I have found that highly eicient radio receiving sets of this type are practically useless within metal enclosures or partial metal enclosures, such as the cabin walls of a steel ship, a steel railroad-car, an automobile, or an aeroplane. Assuming that these enclosures constituted efficient shields for the loop antenna, I found that, by placing` the set so that the loop antenna thereof was in an opening in the enclosure, the normal 'sensitivity or signal pickup of the set was reestablished.

Since it was impracticable to provide unive sally applicable means for supporting radio receiving sets in openings to obtain the results I have just mentioned, I have devised the present novel loop antenna construction and provided it with means by which it may be so supported individually in a convenient and thoroughly practicable manner, as, for example, upon a glass port-closure or window. When so positioned, the loop is located in an opening through the surrounding metal wall of the room, ship, railroadcar, automobile, or aeroplane, as the case may be, and the shielding or blanketing effectv of said wall upon the loop is substantially eliminated.

For convenience in illustrating and describing the application of my device, I have shown ,the loop antenna construction in connection with a portable radio receiving set and applied upon the window of a railroad-car, but it will be understood from the foregoing explanation and the following description that neither its connection nor application is so limited, nor is the invention limited in any sense to the several uses I have mentioned.

In the drawings Figure 1 is a view of a portion of the interior 6 of a railroad-car, showing a portable radio receiving set upon the usual folding table and the loop antennaof my invention in position upon the adjacent car-window;

Fig. 2 is an end elevational view of a portl0 able radio receiving set, with the end wall thereof partly broken away to illustrate the loop antenna of the set constructed and arranged according to one form of my invention;

Fig. 3 is a fragmentary sectional detail view, l5 upon an enlarged scale, illustrating the use of a conventional spring latch for removably holding the loop antenna unit in the position shown-in Figure 2;

Fig. 4 is a front elevational view of the loop 20 antenna construction embodying my invention, viewed in the direction of the arrows 4-4 of Figure 2; and

Fig. 5 is an end elevational view of a radio receiving set, with the end wall ,thereof partly ,25 broken away to illustrate the built-in loop antenna of the set and the plug-in connection of a 'separate loop antenna constructed and arranged according to another form of my invention.

The particular form and construction of the J30 radio receiving apparatus does not form a part of this inventionl and I have therefore illustrated only the general outward appearance of a radio receiving set, having a casing I, a carrying handle 2, a hinged drop-cover 3, control knobs 4 and 5, and a. tuning dial 6.

The loop antenna 1 herein shown is coiled upon the panel 8 and secured thereto in any suitable manner, as by the-at strips 9--9 spanning the coils at spaced distances and stapled as at III- I0 40 to the panel. The panel 8 is secured to a second panel II by means of screws I2-I2, the loop being positioned between the two panels and protected thereby upon its opposite sides. In the arrangement shown in Figures 2 and 3, the panel 45 -II constitutes the removable back of the casing` I, the lower edge-part of the panel being received in a channel or groove I3 along the upper rear edge of the bottom of the casing and the upper edge thereof being held by a releasable spring latch I4. A hand-hole is cut through both panels 8 and II, as at I5, to facilitate removal, replacement, and handling of the loop antenna unit.` The inner and outer ends of the loop are connected with leads I8 and I1, respectively, and these leads are stitched in spaced parallel arrangement along the opposite edges of a flexible tape or webbing I3 of a length suill-l cient to permit the loop antenna. unit to be re.

moved from the casing and individually supported in a manner to be described without requiring disconnection of the leads from the loop or 'from the input leads of the receiver circuit arrangement.

I provide the outer surface of the panel 3 with one or more rubber suction-cups, such as I S, 2l and 2|, secured thereto in any suitable manner, by means of which the entire loop antenna unit may be supported upon the glass window 22, as illustrated in Figure 1, or upon any other suitable ilat surface. As hereinbefore mentioned and as will be apparent from the illustration, when the loop is thus supported upon the window of the car or other enclosing structure, it will be positioned atan opening in the wall of said structure and completely insulated therefrom. In the actual use of the apparatus herein set forth, it has been found that under given conditions there is a denite location for best reception adjacent the opening in the wall. For example, best reception for stations in a given direction. from the opening' may require the antenna to be positioned in the upper left-hand or lower righthand'corner. while for stations in another direction the other corners of the opening may provide best reception. is shown in Figure 2. when the loop antenna unit is returned to its position at the back of the casing I, the tape or webbing I8 is stowed within the casing, and the loop continues to serve as the antenna for the radio receiver. It is to be understood that the removability of the loop antenna unit and the described provision for its individual support do not interfere with orreduce its eiliciency or the eiliciency of the radio receiving set when it is returned to its position ln the casing, as shown in Figure 2, but constitute additional features which permit it to be used satisfactorily in locations and under circumstances which wouldI otherwise be impracticable.

Referring, now, to the construction shown in Figure 5, I have illustrated a radio receiving set similar in general appearance to the set shown in the other figures of the drawings, but which contains a built-in spiral loop antenna, which is indicated at 23 and which may be substantially the same in form and arrangement as the one already described. While the back panel 24 may be made removable for permitting convenient access to the interior of the casing 25, it will be assumed for the purpose of the following description that the loop and the back panel are not intended to be removed excepting for` inspection and repair purposes. Under such circumstances, an additional loop antenna unit may be provided and plugged into connection with the receiving set. I have therefore shown the radio receiving set of Figure provided with a jackcomcast and n of the plug :1. with this arrangement, prior to the insertion of the plug 31, the built-in loop 23 will be connected with the input leads 3| and 32 through loop-leads 26 and 21, contacts 23 and 23, and spring contact-fingers 33 and 3l. Insertion of the plugV 31 will spread spring contact-fingers 33 and 3l, breaking their connections with contacts 28 and 29 an'd thereby disconnecting loop 23, and leads i6 and l1 of the additional loop antenna unit will be connected with the input leads 3i and 32 through engagement of the spring contact-fingers 33 and 3l with the headl and sleeve contacts 35 and 36 of4 the plug 31.

I claim- 1. In a radio receiving set provided with an antenna carried by said set and operative under normal conditions to' receive radio signals, the improvement which comprises means for enhancing reception of said signals under abnormal conditions when said set is positioned Within a shielding structure having an opening therein, said means comprising an elongated flexible member electrically connecting said antenna to said set and means provided on said antenna constructed and arranged for quickly attachably and detachably securing the same to asurface in any one of a plurality of positions relative to said opening and apart from said set.

2. In a radio receiving set provided with an antenna carried by said set and operative under normal conditions to receive radio signals, the improvement which comprises means for enhancing reception of said signals under abnormal conditions when said set is positioned within a shielding structure having an opening therein, said means comprising an elongated flexible member electrically connecting said antennauto said set and vacuum cups carried by said antenna for quickly attachably and detachably securing\the same to surfaces', including vertical surfaces, in any one of a plurality of positions relative to said opening and apart -from said set.

3. In a radio receiving apparatus comprising a radio receiving set operative under normal conditions to receive radio signals, the improvement which comprises, means for enhancing reception of said signals under abnormal conditions when said set is positioned Within a shielding structure having an opening therein, said means comprising an antenna structure including conductors forming a loop attached to a panel, an elongated flexible member electrically connecting said loop to said set, and means provided on said panel forming a unitary structure therewith and constructed and arranged for quickly attachably and detachably securing the same to a surface in any one of a plurality of positions relative to said opening and apart from said set.

4. In a radio receiving set provided 'with an antenna carried by said set and operative under normal conditions to receive radio signals, the improvement which comprises means for enhancing reception of said signals under abnormal conditions when said set is positioned within a shielding structure having an opening therein, said means comprising an elongated flexible member electrically connecting said antenna to said set and means provided on said antenna constructed and arranged for quickly attachably and detachably securing the same to a surface in any one of a plurality of positions relative to said opening and 'apart from said set, said receiving set being provided with a casing and said antenna forming a wall of said casing under said normal conditions.

5. In a radio receiving set provided with an antenna carried by said set and operative under normal conditions to receive radio signals, the improvement which comprises means for enhancing reception of said signals under abnormal conditions when said set is positioned within a shielding structure having an opening therein, said means comprising an elongated flexible member electrically connecting said antenna to said set and means provided on said antenna constructed and arranged for quickly attachably and detachably securing the same to a surface in any one of a plurality of positions relative to said opening and apart from said set, said antenna being of the loop type and including a rigid panel with antenna conductors secured thereto and movable as a unit therewith.

6. In a radio receiving set provided with an antenna carried by said set and operative under normal conditions to receive radio signals, the

improvement which comprises means for enhancing reception of said signals under abnormal conditions when said set is positioned within a shielding structure having an opening therein, said means comprising an elongated flexible member electrically connecting said antenna to said set and means provided on said antenna constructed and arranged for quickly attachably and detachably securing the same to a surface in any one of a. plurality of positions relative to said opening and apart from said set, said receiving set being provided with a casing, said antenna being of the loop type and including a rigid panel with antenna conductors secured thereto, said panel forming a removable wall of said casing under said normal conditions and having a plurality of vacuum cups secured thereto interiorly of said casing to constitute said means constructed and arranged for quickly attachably and detachably securing the same to said surface.

EUGENE F. MCDONALD, JR. 

